Determining the bit error rate (BER) in received transmissions is one way to measure the health of a communications network. The BER is usually given in terms of bit errors divided by the total number of bits. Typical BERs are less than 10−9, while very poor BERs are greater than 10−5. If the BER from a particular node or link in the network is consistently too high, the network may reroute traffic to avoid the source of the errors, and the faulty node/link can be fixed.
Typically, digital data is transmitted within packets or frames in accordance with one of a variety of well known standards. Such packets or frames contain headers, payload data, and other fields and frequently contain thousands of bits. One of these fields is typically an error detection field, such as a cyclic redundancy check (CRC) field that identifies if there is any error in the packet or frame. CRC's used for error detection do not determine the number of bit errors in the frame or packet, although such information would be valuable.
Another problem with bit error detection in present systems is that transmission errors are typically only detected while transmitting packets in the network. Therefore, if a problem occurs in the network, payload data is lost before the problem is detected. In addition, the reliability and speed of detecting the problem depend on the rate at which packets are transmitted.
Accordingly, what is needed is a technique that reliably measures the health of a communications network without suffering from the drawbacks described above.